DE3314048A1 - ANODE ACTIVE MATERIAL, ALKALICELLES CONTAINING THIS MATERIAL AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

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- 6 description

The invention relates to an anode material for batteries and a method for producing the anode material as well as Alkaline cells in which the anode material is used and a method of making the cell. In particular concerns They are an anode active material that is composed of amalgamated zinc powder and is used to develop to prevent gases in alkaline cells, etc., as well as a method for producing the anode-active material and also from improved alkaline cells using the anode active Materials and Methods for Making the Improved Alkali Cells.

In alkaline cells and similar cells in which zinc is used as an anode-active material, these must be closed, because they use strong alkaline electrolytes like aqueous solution of potassium hydroxide. The fact that the cells are closed is particularly important in order to make them compact, while doing so during storage of the cells hydrogen gas evolved by corrosion of the zinc becomes trapped. The gas pressure in the increases accordingly Cells during their long-term storage, with the possible danger such as explosion increasing with increasingly perfect closure of cells increased. Various Cells proposed which are structurally designed that selectively such a generated in the cells Gas is led to the outside; however, the cells known hitherto are not completely satisfactory. It was therefore tried prevent the corrosion of an anode active zinc material in the cells, thereby reducing the evolution of gas within of cells is diminished; as a result of these attempts, amalgamated zinc was used, by which by the high hydrogen overvoltage of mercury is made use of. However, this anode-active material contains

Mitsui Mining ... P 1640-EN

which is used in the currently commercially available alkaline cells, mercury in amounts up to 5 to 15%; through this can harm human health and pollute the environment.

Therefore, alkaline cells have been proposed in which a zinc electrode has lead (Pb) or the like instead of Contains mercury to prevent gas development. Such To a certain extent, substances are suitable for preventing gas development; however, they can with regard to their Efficacy cannot currently be viewed as a substitute for mercury. In addition, a method has been proposed at the zinc powder into an acidic solution containing mercury ions containing Pb, Cd and similar ions to amalgamate the Zinc powder is immersed with simultaneous cementation with the addition of Pb, Cd and the like to the zinc powder; this proposed However, the method is not convincing in terms of reducing the amount of mercury while effectively suppressing it at the same time the gas evolution.

The object of the present invention is therefore, under To circumvent the disadvantages of the prior art, to propose an alkaline cell in which a new anode-active Material is used that significantly reduces the amount of mercury while at the same time effectively suppressing it the evolution of hydrogen gas through the anode-active material and at the same time has improved cell efficiency.

The solution to this problem according to the invention is described below.

According to the invention it has been found that in an ano'denactive Material containing zinc, the simultaneous use of mercury and indium not only lead to the same hydrogen gas evolution and thus to a reduction in the amount of mercury in conventional anode-active material, which is essentially consists of amalgamated zinc, but at the same time the other cell properties are improved; in this fact is one of the essential features of the invention.

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It has also been found that when used with mercury, thallium is another element that, like indium, is essential the evolution of hydrogen gas is reduced. Accordingly, alkaline cells can be provided according to the invention at which the degree of hydrogen gas evolution is substantially reduced while at the same time minimal amounts of mercury are present in the zinc anode.

Conventional anode-active material, which consists essentially of amalgamated zinc powder, contains 5 to 15% Mercury, while the anode-active material according to the invention has a mercury content of, for example, 1% or may have less in order to reduce the gas evolution to at least the same extent as the conventional one, whereby in addition, the cell properties are improved. Of course, the mercury content in the anode-active material be increased according to the invention in order to increase the effectiveness of the anode-active material accordingly. For practical reasons the anode active material of the present invention has a mercury content of about 5% or less, and has higher Effectiveness compared to a conventional material, which is made from an amalgamated zinc powder with 5 to 15% Mercury content.

The indium content of the new anode-active material according to Invention varies depending on the method by which the active material is produced; it can be in the range from 0.01 to 10%, preferably 0.01 to 1.8%.

The anode active material according to the invention which is used as it is in alkali cells according to the invention can be made in different ways such as: 30

(1) a process for amalgamating zinc / indium powder (partially Indium cemented zinc powder),

(2) a method of amalgamating zinc powder with an indium amalgam and

(3) Method of amalgamating a zinc / indium alloy in Powder form.

Mitsui Mining ... P 1640-EN

The anode-active material according to the invention is preferably used manufactured by using powdery zinc / indium / mercury as amalgamated metal powder according to one of the three described Process forms.

The method (1) can be carried out, for example, by dissolving metallic indium or an indium compound in an acid such as hydrochloric acid, heating the whole to remove most of the excess acid as necessary, and diluting the remaining solution with water to obtain a to prepare an aqueous indium salt solution containing a predetermined concentration of indium (for example, 0.1 to 5 g / l as indium). The zinc powder is then introduced into the solution produced in this way in order to ^{react zinc and indium at a temperature of 80 °} C. or lower over a reaction time of 1 to 60 minutes, with indium being applied to the surface of the zinc powder. It is possible to change the amounts of indium for the zinc powder as needed by changing the indium concentration in the indium salt solution, as well as changing the reaction temperature, the reaction time and the like reaction parameters. The zinc / indium powder formed, which has been produced by the deposition of indium on the surface of the zinc powder, is washed with water, dried or undried, and then amalgamated.

The amalgamation can be carried out by various methods, the following being preferred:

A preferred method is that zinc / indium powder, as described, is introduced into an alkali solution, such as an aqueous solution of potassium hydroxide, the mixture formed is first stirred for 1 to 30 minutes, metallic mercury is slowly dripped into the mixture through narrow openings, the Stir whole for 30 to 120 minutes, wash with water. and then dries at low temperatures at 30 to 60 ⁰ C to obtain the zinc / indium / mercury powder. The preferred indium content of the zinc / indium / mercury powder obtained in this way is 0.01 to 1%.

Another method is by mixing indium with mercury to form an indium amalgam and then amalgamated Zinc powder amalgamated with the previously formed indium amalgam. If the zinc powder is amalgamated with the indium amalgan, the zinc powder is contained in the amalgam, while the indium / mercury ratio in the indium amalgam is unchanged is held because mercury is able not only with zinc but also with indium even at room temperature to form an amalgam. It is therefore possible to change the indium and mercury content in zinc powder by changes the indium content in the indium amalgam. Amalgamation can be done in different ways? preferred it is carried out as described above. In particular, the amalgamation is effected by using indium amalgam immersed in an alkali solution to which zinc powder is added. The indium content of the zinc / Indium / mercury powder made by this method from 0.01 to 5%.

Another method is to add indium to the molten zinc to obtain the zinc / indium alloy powder; the alloy powder produced in this way is then amalgamated to form the zinc / indium / mercury powder.

Various methods can be used for amalgamation, most preferably the same method being the previously mentioned, namely the addition of mercury to an alkaline solution containing zinc / indium alloy powder. The zinc / indium / mercury powder produced by this method preferably has an indium content of 0.01 to 10%.

Using a zinc / lead alloy powder (containing 0.005 to 1% lead) instead of the zinc powder (containing not more than 0.003% lead), the method described can be carried out just as smoothly.

The invention is explained in more detail by means of the following examples; the percentages relate to weight, unless otherwise stated.

Mitsui Mining ... P 1640-EN

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example 1

A 0.3 g sample of indium metal was completely dissolved in an excess amount of hydrochloric acid, heated by evaporation to remove most of the excess hydrochloric acid, and then diluted with purified water to prepare 600 ml of an indium chloride solution having an indium concentration of 0.5 g / l having. This solution was charged with 250 g of a commercial zinc powder (35 to 100 mesh) was added to cells or batteries, and then stirred for 30 minutes at 20 ⁰ C, to deposit the indium on the surface of the zinc powder. This zinc / indium powder was washed with purified water, introduced into 1 liter of a 10% strength solution of potassium hydroxide, ^{stirred for 5 minutes at 20 °} C. and then stirred for 60 minutes at 20 ^° C. with the slow addition of such an amount of metallic mercury To achieve a predetermined mercury content, this addition was made drop by drop through narrow openings to achieve amalgamation. After completion of the Amalgamierens amalgamated in this way zinc / indium powder was washed with water and dried for 24 hours at 45 ⁰ C. In this way, four zinc / indium / mercury powders with 0.1% indium content and four different mercury contents, namely 1%, 3%, 5% and 7%, were obtained by adjusting the amount of mercury added accordingly.

This procedure was carried out with the difference that a zinc / lead alloy powder containing 0.005% lead was used in place of the zinc powder; metallic mercury was added in such amounts as to make one 1% content of mercury in the alloy powder formed and a zinc / lead / indium / mercury powder with a content to obtain 0.005% lead, 0.1% indium and 1% mercury.

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Example 2

0.56 g and 5 g of mercury were mixed together to form an indium amalgam containing 10% indium to obtain. This indium amalgam was used to amalgamate zinc powder according to Example 1, wherein a Zinc / indium / mercury powder with a 0.1% content of indium and 1% content of mercury was obtained. In addition, an indium amalgam with 50% indium content was also produced; this indium amalgam was used »to amalgamate zinc powder according to Example 1, a zinc / indium / mercury powder with a 0.1% indium content and 1% mercury content were obtained. In addition, an indium amalgam with 50% indium content was also produced, whereupon this indium amalgam was used for amalgamating zinc powder according to Example 1, a zinc / indium / mercury powder with a 1% content of indium and a 1% content of mercury was obtained.

This procedure was repeated except that 0.1 g of indium and 7.5 g of mercury were used in the preparation an indium amalgam with 1.3% indium content and a Zinc / lead alloy powder with 0.05% lead content was used instead of the zinc powder, with a zinc / lead / indium / Obtained mercury powder with 0.05% content of lead, 0.02% content of indium and 1.5% content of mercury became.

Example 3

A metallic indium piece was introduced into molten zinc; the melt was then cooled and turned into a finely divided zinc / indium alloy powder with 0.1% content processed with indium. This zinc / indium alloy powder was mixed with mercury according to Example 1 to form a zinc /

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Indium / mercury powder with 0.1% indium and 1% mercury content amalgamated.

In addition, indium was added to a molten zinc / lead alloy to produce a zinc / lead / indium alloy powder with 0.1% lead content and 0.1% indium content, whereupon this alloy powder according to Example 1 was converted into a zinc / lead / Indium / mercury powder with 0.1% lead content, 0.1% indium content and 1% mercury content was amalgamated.
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Example 4

0.56 g of thallium and 5 g of mercury were used for the preparation of a thallium amalgam with 10% thallium content mixed together. Then this thallium amalgam became the Amalgamation of zinc powder according to Example 1 used, a zinc / thallium / mercury powder with 0.1% thallium content and 1% mercury content was obtained.

This procedure was repeated with the difference that a zinc / lead alloy powder was used instead of the zinc powder with a 1% lead content was used, a zinc / lead / thallium / mercury powder with a 1% lead content, 0.1% content of thallium and 1% content of mercury was obtained.

The zinc / indium / mercury powder, zinc / lead / indium / mercury powder, zinc / thallium / mercury powder obtained in this way and zinc / lead / thallium / mercury powder were each used as anode active Material used in a hydrogen evolution test. Conventional zinc / mercury powder samples were used for comparison with mercury contents of 1, 3, 5 and 7% as anode active material in the same experiment as described above used.

These attempts for development of gas were carried out at 45 ⁰ C, and 10g of the respective anode active material and as the electrolyte 5 ml of a 40 weight percent aqueous solution of potassium hydroxide saturated with zinc oxide were used. the

Table 1

example 1 (a)
(b)
(C)
(e) Salary (%) lead Indium Thallium 2 mercury Gas development
speed
(ml / g-day) Anode active
Material according to
invention Example 2 (a)
(b)
(C) 0.005 0.1
0.1
0.1
0.1
0.1 I I I I I 1
3
5
7th
1 1.3 x 10 " ³
1.2 x 10 " ³
1.1 x 10 " ³
1.1 χ 10 " ³
0.8 χ 10 ~ ³ Example 3 (a)
(b) 0.05 0.1
1.0
0.02 ; 1
1
1.5 1.1 χ 10 " ³
1.0 χ 10 " ³
0.8 χ 10 " ³ Example 4 (a)
(b) 0.1 0.1
0.1 - H- H- H- H-
H- K)
X X
H- H-
O O
ViJ ViJ Usual anode active
material (a)
(b)
(C) 1.0 - 0.1
0.1 1
1 1.1 χ 10 " ³
0.9 χ 10 " ³ I I I I I I I I - 1
3
5
7th 5.0 χ 10 ~ ³
4.1 χ 10 " ³
1.3 χ 10 " ³
1.3 χ 10 " ³

H-cn cn (D

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It can be seen from Table 1 that each of the anode-active materials containing indium amalgamated according to the invention and manages with significantly reduced amounts of mercury compared to conventional anode-active materials, shows satisfactory results with regard to the inhibiting effect on hydrogen evolution.

Then, the alkali / manganese type cells containing the active materials were examined for their properties. The following cell constructions were used: 10

(1) cathode; 90 parts by weight of a commercially available manganese dioxide powder were mixed with 10 parts by weight of graphite; the resulting mixtures were compression molded.

(2) anode; each of the aforesaid anode active materials was placed on the cathode mix. Between the two A separating film was placed on the electrodes. The amount of any anodenative material that is in this way was used, was 35 parts by weight.

(3) electrolyte; a 40 weight percent aqueous solution of potassium hydroxide saturated with zinc oxide was used.

The test cells prepared in this manner were discharged on a 20-ohm load at 20 ⁰ C; the discharge duration was measured up to a cut-off voltage of 0.9 volts. The discharge time was measured by means of an index number with a value of 100 for conventional active material. The results are shown in Table 2.

Table 2

example 1 (a)
(b)
(C)
(e) Salary (%) lead Indium Thallium mercury Discharge duration
(Cut-off voltage:
0.9 V) Anode active
■ oil material according to
invention Example 2 (a)
(C) 0.005 0. 1
0.1
0.1
0.1 t I Il 1
3
5
1 100
104
104
105 Example 3 (b) 0.05 0.1
0.02 - 1
1 .5 109
105 Example 4 (a)
(b) 0.1 0.1 - 1 105 Usual anode active
material (C) 1 .0 0.1
0.1 1
1 103
105 - - - 5 100

Mitsui Mining ... P 1640-EN

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From Table 2 it can be seen that the test cells that anode-active material (containing amalgamated indium) according to the invention, improved or at least the same discharge properties compared to test cells, the conventional Contain anode-active material, although the anode-active material according to the invention have significantly lower amounts of mercury compared to conventional anode-active material.

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Claims (28)

WILtHELM-S * & Kl-LTAN PATENTANWÄLTE EUROPEAN PATENT ATTORNEYS EUROPEAN PATENT REPRESENTATIVES MANDATAIRES EN BREVETS EUROPEENS DR.ROLF E. WILHELMS DR.HELMUT KILIAN GEIBELSTRASSE 6 80OO MUNICH 47 40 TELEPHONE 34 (0 89) MUNICH 52 TELEPHONE (0 89) ) TELEGRAMS PATRANS MÜNCHEN TELECOPIER gr. 2 (089) 222 066 P T640-DE Mitsui Mining & Smelting Co., Ltd. Tokyo / Japan Anode-active material, alkaline cells containing this material and process for their production Priority: April 19, 1982 - JAPAN - No. 63930/82 June 23, 1982 - JAPAN - No. 106686/82 Claims 1. Anode active material consisting of zinc powder with indium contained therein, the metals being amalgamated, 2. Anode-active material according to claim 1, g e k e η η 5 characterized by an indium content in the range of 0.01 to 10 percent by weight. 3. Anode-active material according to claim 2, g e k e η η is characterized by an indium content in the range from 0.01 to OO IHUHO 1.8 percent by weight. 4. Anode-active material according to claim 1 or 2, characterized characterized in that the mercury content is not higher than 5 percent by weight. 5. Anode-active material according to claim 4, characterized characterized in that the mercury content is not higher than 1 percent by weight. 6. Anode-active material according to claim 1, 2 or 5, characterized characterized in that the zinc powder is substituted by zinc / lead alloy powder. 7. Anode-active material according to claim 4, characterized in that the zinc powder is replaced by a zinc / Lead alloy powder is substituted. 8. Anode-active material according to claim 6 or 7, characterized in that the lead content is in the range from 0.005 to 1 percent by weight. 9. Anode-active material according to claim 1 - 3, 5 and 7, characterized in that the indium is replaced by thallium. 10. Anode-active material according to claim 4, characterized in that the indium is substituted by thallium is. 11. Anode-active material according to claim 6, characterized in that the indium is substituted by thallium is. 12. A method for producing an anode-active material for cells, characterized in that one Mitsui Mining ... P 1640-EN 1 O. f: L ..; "" / ": 33U048 Applying indium to the surface of zinc powder to produce a zinc / indium powder and then amalgamating the zinc / indium powder produced in this way to form a zinc / indium / mercury powder.
5 1 3. The method according to claim 1 2, characterized in that the zinc powder by a zinc / lead alloy powder replaced. 14. Process for the preparation of an anode-active material for cells, characterized in that one Zinc powder amalgamated with indium / amalgam to form a zinc / indium / mercury powder. 15. The method according to claim 14, characterized in that the zinc powder is replaced by a zinc / lead alloy powder replaced. 16. A method for producing an anode-active material for cells, characterized in that one Zinc / indium alloy powder to a zinc / indium / mercury powder amalgamated. 17. The method according to claim 16, characterized in that g e k e η η, that zinc powder is replaced by zinc / lead alloy powder. 18. The method according to any one of claims 12 to 16, characterized characterized in that indium is replaced by thallium. 19. Alkaline cell that has at least one amalgamated metal powder, namely zinc / indium / mercury powder or Contains zinc / lead alloy indium / mercury powder. 20. Alkali cell according to claim 19, characterized in that the indium content of the amalgamated metal powder ranges from 0.01 to 10 weight percent. 21. Alkali cell according to claim 19, characterized in that the mercury content of the amalgamated Metal powder is in the range not higher than 5 weight percent. 22. Alkali cell according to claim 21, characterized in that the mercury content of the amalgamated Metal powder is in the range not higher than 1 weight percent. 23. A method for producing an alkaline cell, wherein indium is applied to the surface of a zinc powder and / or zinc / Applies lead alloy powder, the formed with indium applied powder to a zinc / indium / mercury powder or Zinc / lead alloy indium / mercury powder amalgamated and this amalgamated metal powder as anode-active material used for cells. 24. A method for making an alkaline cell, thereby characterized in that zinc powder with indium amalgam to zinc / indium / mercury as amalgamated metal powder amalgamated, and the amalgamated metal powder thus obtained is used as an anode active material for cells. 25. A method for making an alkaline cell, thereby characterized in that one is a zinc / indium alloy powder amalgamated to a zinc / indium / mercury powder as amalgamated metal powder and then as anode-active Material used for cells. Mitsui Mining ... P 1640-EN 26. The method according to any one of claims 23 to 25, characterized characterized in that the zinc powder is replaced by zinc / lead alloy powder. 27. The method according to any one of claims 23 to 25, characterized characterized in that the indium is replaced by thallium. 28. The method according to claim 26, characterized in that g e k e η η, that indium is replaced by thallium.